Floor Determination via Path Loss Lookup Tables
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Solution Overview
Problem
Conventional location-based service (LBS) techniques in multi-story buildings are error-prone in determining the correct floor of a client device, leading to incorrect location representation and erratic map displays due to reliance on signal strength and number of received signals from reference points across different floors.
Innovation Solution
A method that involves measuring signal strengths from reference points, calculating a confidence level for floor selection using candidate floor selection methods, and adjusting this level based on proximity to known entry/exit points, employing adaptive path loss models to improve accuracy in determining the current floor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional trilateration techniques are used to determine floor location based on received signal strength, then the system can operate with simple algorithms, but the floor determination accuracy deteriorates leading to incorrect floor detection
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing path loss characteristics for each floor in a lookup table during a setup phase. This allows the runtime floor determination to use simple comparisons rather than complex real-time calculations, resolving the contradiction between accuracy and computational simplicity
Solution Approach 2:
The patent applies beforehand cushioning by storing compensatory path loss data for each floor in advance. This pre-stored information acts as a cushion that compensates for signal variations and environmental factors, enabling accurate floor detection without requiring complex real-time signal processing
2Reliability
If the system relies on the strongest received signal to determine current floor, then the algorithm remains simple, but reliability deteriorates when signals from multiple floors are comparable in strength
Solution Approach 1:
The system changes the parameter used for floor determination from simple signal strength comparison to path loss characteristic matching. By transforming the problem into comparing path loss values stored in a lookup table, the system achieves higher reliability while maintaining algorithmic simplicity
Solution Approach 2:
The patent introduces an intermediary element - the path loss lookup table - that mediates between the raw received signal strength and the final floor determination. This intermediary structure enables reliable floor detection by providing pre-computed reference values that account for environmental variations
3Adaptability or versatility
If the system uses basic signal strength comparison without environmental adaptation, then the implementation remains simple, but adaptability to different building environments deteriorates
Solution Approach 1:
The system performs preliminary calibration actions during a setup phase to capture environment-specific path loss characteristics and store them in a lookup table. This preliminary adaptation enables the system to automatically adjust to different building environments without requiring complex runtime calibration procedures
Data Source
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AI summary
A device stores an indication of a current floor of a multiple floor building on which a device is located. The device measures signal strengths of signals received at the device from transmitters having known locations on the floors of the building. The device selects one of the multiple floors as a candidate floor based in part on the measured signal strengths. The device increases a confidence level associated with the indication of the current floor if the candidate floor corresponds to the current floor, and decreases the confidence level if the candidate floor does not correspond to the current floor. The device replaces the indication of the current floor with the candidate floor if the confidence level is below a threshold.